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    <title>iirgroup</title>
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    <center>Scilab Function</center>
    <div align="right">Last update : April 1993</div>
    <p>
      <b>iirgroup</b> -  group delay Lp IIR filter optimization</p>
    <h3>
      <font color="blue">Calling Sequence</font>
    </h3>
    <dl>
      <dd>
        <tt>[lt,grad]=iirgroup(p,r,theta,omega,wt,td)  </tt>
      </dd>
      <dd>
        <tt>[cout,grad,ind]=iirlp(x,ind,p,[flag],lambda,omega,ad,wa,td,wt)  </tt>
      </dd>
    </dl>
    <h3>
      <font color="blue">Parameters</font>
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    <ul>
      <li>
        <tt>
          <b>r</b>
        </tt>: vector of the module of the poles and the zeros of the filters</li>
      <li>
        <tt>
          <b>theta</b>
        </tt>: vector of the argument of the poles and the zeros of the filters</li>
      <li>
        <tt>
          <b>omega</b>
        </tt>: frequencies where the filter specifications are given</li>
      <li>
        <tt>
          <b>wt</b>
        </tt>: weighting function for and the group delay</li>
      <li>
        <tt>
          <b>td</b>
        </tt>: desired group delay</li>
      <li>
        <tt>
          <b>lt, grad</b>
        </tt>: criterium and gradient values</li>
    </ul>
    <h3>
      <font color="blue">Description</font>
    </h3>
    <p>
    optimization of IIR filters for the Lp criterium for the
    the group delay. (Rabiner &amp; Gold pp270-273).</p>
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